MdePkg/Library/BaseLib/SynchronizationGcc.c

   1 /** @file
   2   Implementation of synchronization functions.
   3
   4   Copyright (c) 2006 - 2007, Intel Corporation<BR>
   5   All rights reserved. This program and the accompanying materials
   6   are licensed and made available under the terms and conditions of the BSD License
   7   which accompanies this distribution.  The full text of the license may be found at
   8   http://opensource.org/licenses/bsd-license.php
   9
  10   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  11   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  12
  13   Module Name:  SynchronizationGcc.c
  14
  15 **/
  16
  17 #include "BaseLibInternals.h"
  18
  19 //
  20 // GCC inline assembly for Read Write Barrier
  21 //
  22 #define _ReadWriteBarrier() do { asm volatile ("": : : "memory"); } while(0)
  23
  24 #define SPIN_LOCK_RELEASED          ((UINTN) 1)
  25 #define SPIN_LOCK_ACQUIRED          ((UINTN) 2)
  26
  27 /**
  28   Retrieves the architecture specific spin lock alignment requirements for
  29   optimal spin lock performance.
  30
  31   This function retrieves the spin lock alignment requirements for optimal
  32   performance on a given CPU architecture. The spin lock alignment must be a
  33   power of two and is returned by this function. If there are no alignment
  34   requirements, then 1 must be returned. The spin lock synchronization
  35   functions must function correctly if the spin lock size and alignment values
  36   returned by this function are not used at all. These values are hints to the
  37   consumers of the spin lock synchronization functions to obtain optimal spin
  38   lock performance.
  39
  40   @return The architecture specific spin lock alignment.
  41
  42 **/
  43 UINTN
  44 EFIAPI
  45 GetSpinLockProperties (
  46   VOID
  47   )
  48 {
  49   // @bug May use a PCD entry to determine this alignment.
  50   return 32;
  51 }
  52
  53 /**
  54   Initializes a spin lock to the released state and returns the spin lock.
  55
  56   This function initializes the spin lock specified by SpinLock to the released
  57   state, and returns SpinLock. Optimal performance can be achieved by calling
  58   GetSpinLockProperties() to determine the size and alignment requirements for
  59   SpinLock.
  60
  61   If SpinLock is NULL, then ASSERT().
  62
  63   @param  SpinLock  A pointer to the spin lock to initialize to the released
  64                     state.
  65
  66   @return SpinLock
  67
  68 **/
  69 SPIN_LOCK *
  70 EFIAPI
  71 InitializeSpinLock (
  72   OUT     SPIN_LOCK                 *SpinLock
  73   )
  74 {
  75   ASSERT (SpinLock != NULL);
  76
  77   _ReadWriteBarrier();
  78   *SpinLock = SPIN_LOCK_RELEASED;
  79   _ReadWriteBarrier();
  80
  81   return SpinLock;
  82 }
  83
  84 /**
  85   Waits until a spin lock can be placed in the acquired state.
  86
  87   This function checks the state of the spin lock specified by SpinLock. If
  88   SpinLock is in the released state, then this function places SpinLock in the
  89   acquired state and returns SpinLock. Otherwise, this function waits
  90   indefinitely for the spin lock to be released, and then places it in the
  91   acquired state and returns SpinLock. All state transitions of SpinLock must
  92   be performed using MP safe mechanisms.
  93
  94   If SpinLock is NULL, then ASSERT().
  95   If SpinLock was not initialized with InitializeSpinLock(), then ASSERT().
  96   If PcdSpinLockTimeout is not zero, and SpinLock is can not be acquired in
  97   PcdSpinLockTimeout microseconds, then ASSERT().
  98
  99   @param  SpinLock  A pointer to the spin lock to place in the acquired state.
 100
 101   @return SpinLock
 102
 103 **/
 104 SPIN_LOCK *
 105 EFIAPI
 106 AcquireSpinLock (
 107   IN OUT  SPIN_LOCK                 *SpinLock
 108   )
 109 {
 110   UINT64                            Tick;
 111   UINT64                            Start, End;
 112   UINT64                            Timeout;
 113
 114   Tick = 0;
 115   Start = 0;
 116   End = 0;
 117   if (PcdGet32 (PcdSpinLockTimeout) > 0) {
 118     Tick = GetPerformanceCounter ();
 119     Timeout = DivU64x32 (
 120                 MultU64x32 (
 121                   GetPerformanceCounterProperties (&Start, &End),
 122                   PcdGet32 (PcdSpinLockTimeout)
 123                   ),
 124                 1000000
 125                 );
 126     if (Start < End) {
 127       Tick += Timeout;
 128     } else {
 129       Tick -= Timeout;
 130     }
 131   }
 132
 133   while (!AcquireSpinLockOrFail (SpinLock)) {
 134     CpuPause ();
 135     ASSERT ((Start < End) ^ (Tick <= GetPerformanceCounter ()));
 136   }
 137   return SpinLock;
 138 }
 139
 140 /**
 141   Attempts to place a spin lock in the acquired state.
 142
 143   This function checks the state of the spin lock specified by SpinLock. If
 144   SpinLock is in the released state, then this function places SpinLock in the
 145   acquired state and returns TRUE. Otherwise, FALSE is returned. All state
 146   transitions of SpinLock must be performed using MP safe mechanisms.
 147
 148   If SpinLock is NULL, then ASSERT().
 149   If SpinLock was not initialized with InitializeSpinLock(), then ASSERT().
 150
 151   @param  SpinLock  A pointer to the spin lock to place in the acquired state.
 152
 153   @retval TRUE  SpinLock was placed in the acquired state.
 154   @retval FALSE SpinLock could not be acquired.
 155
 156 **/
 157 BOOLEAN
 158 EFIAPI
 159 AcquireSpinLockOrFail (
 160   IN OUT  SPIN_LOCK                 *SpinLock
 161   )
 162 {
 163   SPIN_LOCK   LockValue;
 164   VOID        *Result;
 165
 166   ASSERT (SpinLock != NULL);
 167
 168   LockValue = *SpinLock;
 169   ASSERT (LockValue == SPIN_LOCK_ACQUIRED || LockValue == SPIN_LOCK_RELEASED);
 170
 171   _ReadWriteBarrier ();
 172   Result = InterlockedCompareExchangePointer (
 173              (VOID**)SpinLock,
 174              (VOID*)SPIN_LOCK_RELEASED,
 175              (VOID*)SPIN_LOCK_ACQUIRED
 176            );
 177
 178   _ReadWriteBarrier ();
 179   return (BOOLEAN) (Result == (VOID*) SPIN_LOCK_RELEASED);
 180 }
 181
 182 /**
 183   Releases a spin lock.
 184
 185   This function places the spin lock specified by SpinLock in the release state
 186   and returns SpinLock.
 187
 188   If SpinLock is NULL, then ASSERT().
 189   If SpinLock was not initialized with InitializeSpinLock(), then ASSERT().
 190
 191   @param  SpinLock  A pointer to the spin lock to release.
 192
 193   @return SpinLock
 194
 195 **/
 196 SPIN_LOCK *
 197 EFIAPI
 198 ReleaseSpinLock (
 199   IN OUT  SPIN_LOCK                 *SpinLock
 200   )
 201 {
 202   SPIN_LOCK    LockValue;
 203
 204   ASSERT (SpinLock != NULL);
 205
 206   LockValue = *SpinLock;
 207   ASSERT (LockValue == SPIN_LOCK_ACQUIRED || LockValue == SPIN_LOCK_RELEASED);
 208
 209   _ReadWriteBarrier ();
 210   *SpinLock = SPIN_LOCK_RELEASED;
 211   _ReadWriteBarrier ();
 212
 213   return SpinLock;
 214 }
 215
 216 /**
 217   Performs an atomic increment of an 32-bit unsigned integer.
 218
 219   Performs an atomic increment of the 32-bit unsigned integer specified by
 220   Value and returns the incremented value. The increment operation must be
 221   performed using MP safe mechanisms. The state of the return value is not
 222   guaranteed to be MP safe.
 223
 224   If Value is NULL, then ASSERT().
 225
 226   @param  Value A pointer to the 32-bit value to increment.
 227
 228   @return The incremented value.
 229
 230 **/
 231 UINT32
 232 EFIAPI
 233 InterlockedIncrement (
 234   IN      UINT32                    *Value
 235   )
 236 {
 237   ASSERT (Value != NULL);
 238   return InternalSyncIncrement (Value);
 239 }
 240
 241 /**
 242   Performs an atomic decrement of an 32-bit unsigned integer.
 243
 244   Performs an atomic decrement of the 32-bit unsigned integer specified by
 245   Value and returns the decremented value. The decrement operation must be
 246   performed using MP safe mechanisms. The state of the return value is not
 247   guaranteed to be MP safe.
 248
 249   If Value is NULL, then ASSERT().
 250
 251   @param  Value A pointer to the 32-bit value to decrement.
 252
 253   @return The decremented value.
 254
 255 **/
 256 UINT32
 257 EFIAPI
 258 InterlockedDecrement (
 259   IN      UINT32                    *Value
 260   )
 261 {
 262   ASSERT (Value != NULL);
 263   return InternalSyncDecrement (Value);
 264 }
 265
 266 /**
 267   Performs an atomic compare exchange operation on a 32-bit unsigned integer.
 268
 269   Performs an atomic compare exchange operation on the 32-bit unsigned integer
 270   specified by Value.  If Value is equal to CompareValue, then Value is set to
 271   ExchangeValue and CompareValue is returned.  If Value is not equal to CompareValue,
 272   then Value is returned.  The compare exchange operation must be performed using
 273   MP safe mechanisms.
 274
 275   If Value is NULL, then ASSERT().
 276
 277   @param  Value         A pointer to the 32-bit value for the compare exchange
 278                         operation.
 279   @param  CompareValue  32-bit value used in compare operation.
 280   @param  ExchangeValue 32-bit value used in exchange operation.
 281
 282   @return The original *Value before exchange.
 283
 284 **/
 285 UINT32
 286 EFIAPI
 287 InterlockedCompareExchange32 (
 288   IN OUT  UINT32                    *Value,
 289   IN      UINT32                    CompareValue,
 290   IN      UINT32                    ExchangeValue
 291   )
 292 {
 293   ASSERT (Value != NULL);
 294   return InternalSyncCompareExchange32 (Value, CompareValue, ExchangeValue);
 295 }
 296
 297 /**
 298   Performs an atomic compare exchange operation on a 64-bit unsigned integer.
 299
 300   Performs an atomic compare exchange operation on the 64-bit unsigned integer specified
 301   by Value.  If Value is equal to CompareValue, then Value is set to ExchangeValue and
 302   CompareValue is returned.  If Value is not equal to CompareValue, then Value is returned.
 303   The compare exchange operation must be performed using MP safe mechanisms.
 304
 305   If Value is NULL, then ASSERT().
 306
 307   @param  Value         A pointer to the 64-bit value for the compare exchange
 308                         operation.
 309   @param  CompareValue  64-bit value used in compare operation.
 310   @param  ExchangeValue 64-bit value used in exchange operation.
 311
 312   @return The original *Value before exchange.
 313
 314 **/
 315 UINT64
 316 EFIAPI
 317 InterlockedCompareExchange64 (
 318   IN OUT  UINT64                    *Value,
 319   IN      UINT64                    CompareValue,
 320   IN      UINT64                    ExchangeValue
 321   )
 322 {
 323   ASSERT (Value != NULL);
 324   return InternalSyncCompareExchange64 (Value, CompareValue, ExchangeValue);
 325 }
 326
 327 /**
 328   Performs an atomic compare exchange operation on a pointer value.
 329
 330   Performs an atomic compare exchange operation on the pointer value specified
 331   by Value. If Value is equal to CompareValue, then Value is set to
 332   ExchangeValue and CompareValue is returned. If Value is not equal to
 333   CompareValue, then Value is returned. The compare exchange operation must be
 334   performed using MP safe mechanisms.
 335
 336   If Value is NULL, then ASSERT().
 337
 338   @param  Value         A pointer to the pointer value for the compare exchange
 339                         operation.
 340   @param  CompareValue  Pointer value used in compare operation.
 341   @param  ExchangeValue Pointer value used in exchange operation.
 342
 343 **/
 344 VOID *
 345 EFIAPI
 346 InterlockedCompareExchangePointer (
 347   IN OUT  VOID                      **Value,
 348   IN      VOID                      *CompareValue,
 349   IN      VOID                      *ExchangeValue
 350   )
 351 {
 352   UINT8  SizeOfValue;
 353
 354   SizeOfValue = sizeof (*Value);
 355
 356   switch (SizeOfValue) {
 357     case sizeof (UINT32):
 358       return (VOID*)(UINTN)InterlockedCompareExchange32 (
 359                              (UINT32*)Value,
 360                              (UINT32)(UINTN)CompareValue,
 361                              (UINT32)(UINTN)ExchangeValue
 362                              );
 363     case sizeof (UINT64):
 364       return (VOID*)(UINTN)InterlockedCompareExchange64 (
 365                              (UINT64*)Value,
 366                              (UINT64)(UINTN)CompareValue,
 367                              (UINT64)(UINTN)ExchangeValue
 368                              );
 369     default:
 370       ASSERT (FALSE);
 371       return NULL;
 372   }
 373 }